I was reading a nice, if slightly dated, set of articles about the new features in Windows Vista, including ars technica's rundown. This article mentions that not much of the functionality avaliable in the Desktop Window Manager (Aero to everyone else) is going to be exposed to third parties, which I think it a great shame.
However, quick investigation reveals that, at least, the thumbnaling stuff has an API.
A quick combination (and about an hour trying to work out a decent layout algorithm) gives:
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